High alumina cement, also called aluminous cement or calcium aluminate cement, is produced by fusing a mixture of limestone and bauxite at high temperatures comprised between 1400 and 1600° C., hence obtaining a melt which after cooling is ground to fine cement. The fusion may be performed in shaft furnaces, like blast furnaces, or in rotary kilns.
In typical formulations for the preparation of high alumina cement, the content of SiO2 may vary from 0.4 to 10.0% by weight, Al2O3 may vary from 25 to 85% by weight and CaO from 15 to 50% by weight. High alumina cement may be used as hydraulic binder for the preparation of concrete intended for construction purposes or in the manufacture of refractory elements. It may also be mixed with other cements for the preparation of cement blends showing specific properties. High alumina cement is known for its rapid strength development.
The production of high alumina cement requires high energy inputs, and there is an ever increasing need for improvement of the energy efficiency of the manufacturing process.
Moreover, because of the highly corrosive nature of the raw materials and melt to be treated, the refractory lining of the furnaces in which the high alumina cement is treated needs to be repaired or replaced after relatively short time periods. There is hence a need to find a way to overcome that technical problem.